The present invention relates to an apparatus for rejecting defective folded printed products from a processing line.
Folded printed products of the type with which the present invention is concerned each comprise a plurality over overlying printed sheets, which are commonly referred to as signatures, and which are assembled into various book forms. The products are serially conveyed in a straddling relation on a gathering conveyor, upon which the individual sheets or signatures are deposited to make up the products, and the conveyor conveys the products through the various assembly operations, which typically include a stitching or binding operation and a trimming operation.
Malfunctions can occur in the delivery of the individual sheets or signatures onto the gathering conveyor, which can result, for example, in a sheet being missing, or in duplicate sheets being delivered, or in a sheet being mis-positioned. Such malfunctions lead to the production of a defective book or magazine, which must then be discarded.
In the prior art, various detectors have been provided which monitor for such malfunctions, with a non-standard product being ejected from the production line. In one known detector, the thickness of each product is measured, and if the measured thickness does not conform to the predetermined standard, the product is removed by a removal device which comprises cammed rollers which physically move into engagement with the defective product and convey it to a reject receptacle. This known removal gate is structurally complex and unreliable in operation.
In another prior reject gate, a blade is utilized to lift a defective product into a nip formed by rollers, which then convey the product to a reject receptacle. The blade must advance and completely retract before the next product arrives on the conveyor, and since such movement involves a relatively significant time period, the production speed of the gathering conveyor is limited.
It is accordingly an object of the present invention to provide an apparatus for ejecting defective products of the described type from a processing line, which is of simplified construction and highly reliable in operation.
It is a further object of the present invention to provide a product rejecting gate of the described type which can be operated at high speed so as to not limit the product speed of the conveyor.
It is also an object of the present invention to provide a product rejecting gate of the described type which is able to remove a defective product without tearing or damaging the product, and so that the product can be easily recycled onto the chain conveyor, thereby avoiding the loss and wastage of the product materials.